Chap. X. TRANSMISSION OF MOTOR IMPULSE. 237 



if the motor impulse was transmitted from the centre 

 across the disc more readily in a longitudinal than 

 in a transverse direction ; and as this appeared a 

 new and interesting fact in the physiology of plants, 

 thirty-five fresh experiments were made to test its 

 truth. Minute bits of meat were placed on a single 

 gland or on a few glands, on the right or left side of 

 the discs of eighteen leaves ; other bits of the same 

 size being placed on the distal or proximal ends of 

 seventeen other leaves. Now if the motor impulse 

 were transmitted with equal force or at an equal rate 

 through the blade in all directions, a bit of meat 

 placed at one side or at one end of the disc ought to 

 affect equally all the tentacles situated at an equal 

 distance from it; but this certainly is not the case. 

 Before giving the general results, it may be well to 

 describe three or four rather unusual cases. 



(1) A miniite fragment of a fly was placed on one side of the 

 disc, and after 32 m. seven of tlie outer tentacles near the frag- 

 ment were inflected ; after 10 hi-s. several more became so, and 

 after 23 hrs. a still greater number ; and now the blade of the 

 leaf on this side was bent inwards so as to stand up at right 

 angles to the other side. Neither the blade of the leaf nor a 

 single tentacle on the opposite side was affected; the line of 

 separation between the two halves extending from the footstalk 

 to the apex. The leaf remained in this state for three days, 

 and on the fourth day began to re-expand; not a single ten- 

 tacle having been inflected on the opposite side. 



(2) I will here give a case not included in the above thirty- 

 five experiments. A small fly was found adhering by its feet to 

 the left side of the disc. The tentacles on this side soon closed 

 in and killed the fly ; and owing probably to its struggle whilst 

 alive, the leaf was so much excited that in about 24 hrs. all the 

 tentacles on the opposite side became inflected; but as they 

 found no prey, for their glands did not reach the fly, they re- 

 expanded in the course of 15 hrs. ; the tentacles on the left side 

 remaining clasped for several days. 



(3) A bit of meat, rather larger than those commonly used. 



